Participants in the study were 263 healthy men and women aged 50-70 years at the start of the study. They were tested at baseline and again six years later to determine their levels of depressive symptoms and interleukin-6. Levels of C-reactive protein, another inflammatory protein, were also measured but were not related to depression.
The strength of the association of depression with future heart disease is similar to that of traditional risk factors like smoking, high blood pressure and elevated cholesterol, according to Dr. Stewart.
"Promotion of inflammation may be one pathway through which depression may 'get under the skin' to negatively influence cardiovascular health. The link to cardiovascular disease demonstrates that there may be physical as well as mental health reasons to treat depression," said Dr. Stewart.
Co-authors of "A Prospective Evaluation of the Directionality of the Depression-Inflammation Relationship" are Kevin Rand, Ph.D., of the Department of Psychology in the School of Science at IUPUI; Matthew Muldoon, M.D., M.P.H., and Thomas Kamarck, Ph.D., of the University of Pittsburgh.
This study was funded by the National Heart, Lung, and Blood Institute.
Source: Indiana University School of Medicine